public class test {
    public static void main(String[] args) {
        Observable po=new postman();

        Observer observer1=new boy("tom");
        Observer observer2=new boy("king");
        Observer observer3=new girl("anlecs");
        po.add(observer1);
        po.add(observer2);
        po.add(observer3);

        po.notify("快递到了");
    }
}
